Backplane manufacture

ABSTRACT

A method is described for manufacturing a backplane in which plugs are inserted into apertures in the backplane to mask the surfaces of the apertures. A nonconductive coating is formed on the backplane while the plugs are positioned in such apertures. Thereafter, electrical contacts are inserted into the apertures to remove the plugs therefrom.

United States Patent [191 Anhalt et a1.

[4 1 Mar. 19, 1974 BACKPLANE MANUFACTURE [75] 1 Inventors: John W.Anhalt, La Crescenta;

David S. Goodman, Orange, both of Calif.

[73] Assignee: International Telephone and Telegraph Corporation, NewYork, NY.

[22] Filed: Dec. 7, 1972 [21] Appl. No.: 312,812

52] US. on. 29/625, 29/212 R [51] rm. Cl. H05k 13/04, B23q 7/10 [58]Field of Search 29/212 R, 200 R, 200 D,

[56] References Cited UNITED STATES PATENTS Grupp 29/212 R Freehauf eta1 29/625 Shaheen 29/625 Primary Examiner-Thomas H. Eager Attorney,Agent, or Firm-Thomas L. Peterson [57] ABSTRACT A method is describedfor manufacturing a backplane in which plugs are inserted into aperturesin the backplane to mask the surfaces of the apertures. A nonconductivecoating is formed on the backplane while the plugs are positioned insuch apertures. Thereafter, electrical contacts are inserted into theapertures to remove the plugs therefrom.

5 Claims, 11 Drawing Figures PAT MARIQIQ? SHEET 1 BF 2 1 BACKPLANEMANUFACTURE BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION Thisinvention relates generally to backplane manufacture and, moreparticularly, to an improved method for manufacturing backplanes.

2. DESCRIPTION OF THE PRIOR ART Backplane connector technology is theart of mounting and arranging electrical contacts on a metal plate,typically an aluminum alloy. Such a plate is usually machine-punched toprovide a plurality of apertures positioned in a precise grid. Afterpunching the apertures, the backplane is anodized to provide acorrosionpreventing and electrically non-conductive surface layer. Theapertures are used for mounting and positioning backplane connectorcontacts. It is necessary that the contacts be conductively insertedinto the anodized backplane. To obtain this conductive connectionusually requires drilling or reaming of the apertures to remove theanodizing layer The anodizing layer is a very hard material anddifficult to remove. Thus, the reaming operation is time-consuming andcostly. Therefore, what is needed and constitutes the principal objectof the present invention, is to provide an improved method forinhibiting the anodizing layer from the surface of backplane apertures.

SUMMARY OF THE INVENTION According to the principal aspect of thepresent invention, after a backplane has been punched to provide aplurality of apertures therein, plugs are inserted in selected aperturesto mask the surfaces thereof. The backplane is then anodized, while theplugs are positioned in such apertures, so that the surfaces of theapertures will not be anodized. In those apertures where it is desiredto make an electrical connection to the backplane, the plugs are removedtherefrom, preferably by inserting the electrical contacts into theapertures thereby forcing the plugs out of the apertures in a singlestep. Thus, by this invention, the step of reaming apertures inbackplanes is eliminated thereby substantially reducing the time andexpense in manufacturing backplanes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of thetool of the present invention used for inserting plugs in a backplane, aportion of the backplane being illustrated adjacent the forward end ofthe tool;

FIG. 2 is a partial vertical sectional view taken along line 2-2 of FIG.1 showing a plug in the tool in position tobe driven into a backplaneaperture;

FIG. 3 is a partial sectional view similar to FIG. 2 showing the toolafter it has inserted a plug into the backplane aperture;

FIG. 4 is a transverse sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is a transverse sectional view taken along line 5-5 of-FIG. 3;

FIG. 6 is an end view of the tool taken along lines 6-6 of FIG. 2; 1

FIG. 7 is an enlarged horizontal sectional view take along line 7-7 ofFIG. 2 showing the indexing mechanism of the tool;

' FIG. 8 is an enlarged side elevation of a series of plugs connected toa common carrier strip;

FIG. 9 is a transverse sectional view taken along 9-9 of FIG. 8;

FIG. '10 is a partial sectional view taken through a backplane showing aplug mounted therein with an electrical contact positioned to beinserted into the backplane aperture carrying the plug; and

FIG. 11 is a sectional view similar to FIG. 10 showing the contactmounted in the backplane aperture and the plug removed therefrom.

DESCRIPTION OF THE PREFERRED EMBODIMENT According to the method of thepresent invention, a backplane, normally an aluminum plate, is punchedto provide a plurality of apertures therein. Plastic plugs are theninserted into selected apertures in the backplane to mask the surfacesof the apertures. Thereafter the backplane is anodized while the plugsare positioned in such apertures to provide a non-conductive coating onthe backplane except upon the surfaces of the apertures masked by theplugs. In those apertures where it is desired to position an electricalcontact for electrical connection to the backplane, the plug in theaperture is removed and a contact inserted therein. Preferably, this isaccomplished in a single step by forcing the contact, or a metallicbushing carrying the contact, into the aperture simultaneously removingthe plug from the aperture. Thus, reaming of the backplane apertures isnot necessary since no anodization has occurred where the plugs aremounted in the apertures. Thus, a substantial reduction in manufacturingtime and expense in manufacturing backplanes is provided by the presentinvention.

Reference is now made to the drawings which illustrate the plastic plugsutilized in the method of the present invention and a tool for insertingthe plugs in backplane apertures. The plugs, generally designated 10,are cylindrical plastic elements formed at their forward ends with'achamfered guiding surface 12 and at their rear ends with an outwardlyextending flange 14. The plugs are connected in parallel juxtapositionto a common flexible carrier strip 16 by tongues 18. The strip 16extends transversely of the plugs 10 and is formed on its lower surfacewith teeth 20 in alignment with the plugs. The tongues 18 are ofgenerally triangular configuration. The base 22 of each tongue isadjacent to and integral with the strip 16. The tongue extends laterallyfrom the strip adjacent to its upper surface 24. The apex or narrowsection 26'of the triangular tongue is integral with and connected tothe bottom 28 of flange 14 on the plug. Thus, the upper surface 24 ofthe strip 16, the tongue 18, and the bottom of the plug lie insubstantially the same horizontal plane.

Referring now to FIG. 1, there is seen a section of a backplane 30having a plurality of apertures 32 formed therein. Plugs 10 are shown asbeing positioned in two of the apertures. The tool for inserting theplugs in the backplane apertures, generally indicated by referencenumeral 34, comprises an elongated, cylindrical barrel 36 having aplunger 38 slidably mounted within the bore 40 within the barrel. Aretaining cap 42 is threadably mounted on the rear portion of the barrel36. A stem 44 on the plunger 38 extends outwardly through an opening 46in the cap and terminates in a handle 48.

The bore of the barrel 36 terminates in a shoulder which is spaced fromthe forward end 52 of the barre]. A reduced diameter bore 54 extendsfrom the bore 40 to such forward end. A transverse slot 55 extends fromthe bore 54 to one side of the barrel 36 as best seen in FIGS. 1 and 6.As seen in FIGS. 2 and 3, a transversely extending passageway 56 passesthrough the barrel body 36 and intersects the bottom of the bore 54 nearthe rear of the bore but forward of the shoulder 50. The sidewalls ofthe passageway 56 are spaced apart a distance slightly greater than thewidth of .the teeth 20 on the carrier strip 16 which carries the plugs10. The height of the slot 55 is sufficient to receive the plugs 10carried by the strip 16. The strip of plugs is fed through thepassageway 56 by an indexing wheel 58 which is rotatably mounted in agenerally horizontally extending cavity 60 extending to the oppositesidewalls of the barrel 36. As best seen in FIG. 1, the wheel 58projects from the sides of the barrel so that it can be turned by thumband finger and held in position to align successive plugs 10 with thebore 54. The wheel 58 is rotatably mounted in the cavity 60 by means ofacylindrical boss 62 which extends into a vertically extendingcylindrical opening 64 in the lower wall of the barrel 36.

A longitudinally extending channel 66 of generally square cross-sectionis formed in the lower portion of the plunger 38. A pawl or detent bar68 is slidably mounted in the forward portion of the channel 66 and isurged in a forward direction by means ofa coil spring 50 lyinglengthwise in the channel. The forward portion of the pawl 68 is formedwith a curved surface 70, as best seen in FIG. 7, which is engageablewith concave recesses 72 formed about the outer periphery of theindexing wheel 58. The spring biased pawl serves to releasably hold thewheel in a position wherein the respective plugs 10 on the strip 16 arein alignment with the bore 54. Upstanding pins 74 extend from the uppersurface 76 of the wheel 58 intermediate the recesses 72. These pins areofa height which allows them to engage the sides of the teeth 20 on thecarrier strip 16 so that upon rotation of the indexing wheel the stripwill be fed through the transverse passageway 56.

The plunger 38 is provided at its forward end with a small cylindricalsection 80 of a diameter less than that of the bore 54 in the forwardend of the barrel. The forward section 80 of the plunger is dimensionedso that its lower surface 82 is spaced above the bottom of the bore 54 adistance slightly greater than the thickness of the tongue 18 on thecarrier strip 16 so that the forward section of the plunger may slideover the upper surface of the tongue 18. A guide pin 84 is formed on theforward section 80 of the plunger. This pin has a diameter slightly lessthan the diameter of the bore 86 in the plug 10 and is coaxial therewithwhen the plug is positioned within the bore 54 of the barrel. In the useof the tool 34 in the method of the present invention, the tool isaligned with an aperture 32 in the backplane 30. The strip 16 carryingthe plugs 10 is fed through the passageway 56 of the barrel by rotatingthe indexing wheel 58. When a plug is brought into alignment with thebore 54 as seen in FIG. 2, the plunger 38 is moved forwardly to insertthe pin 84 within the plug bore 86. After the pin is forwardly insertedin such bore, the shoulder 86 formed between the pin and the forwardsection 80 of the barrel engages the rear 90 of the plug. Furtherforward movement of the plunger will cause the tongue 18 to tear at itsconnection to the plug at the apex 26 and the plug will be moved out ofthe bore 54 and driven into the aperture 32 in the backplane, as seen inFIG. 3. Thereafter, the plunger is retracted and the indexing wheelrotated to bring successive plugs into alignment with the bore 54 of thebarrel for further plugging operations.

Reference is now made to FIGS. 10 and 11 which illustrate an electricalcontact element which is mounted in a metal bushing 102. The contact ispassed through the plug 10 in the backplane 30 until the bushing engagesthe plug. The bushing is then forced in a rightward direction asindicated by the arrow in FIG. 10 to push the plug 10 out of thebackplane aperture 32 so that the bushing replaces the plug as seen inFIG. 11. If desired, the bushing 102 can be eliminated and the contact100, if formed with a sufficiently wide body portion, may bepress-fitted directly in the aperture 32. Thus, in a single step, theplug 10 is removed from the backplane aperture 32 and an electricalcontact is positioned in the backplane in electrical engagementtherewith. Alternatively, the plug 10 may be removed from the backplanein one step and the contact mounted in the backplane in a secondsubsequent step. In either case, by the method of the present invention,wherein the aperture surfaces 32 are masked during the anodizingprocedure, the time-consuming and expensive procedure of reaming platedbackplane apertures is eliminated.

Although we have herein shown and described our invention in what wehave conceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of ourinvention which is not to be limited to the details disclosed herein butit to be accorded the full scope of the claims so as to embrace any andall equivalent structures and methods.

What is claimed is: 1. In the method of manufacturing a backplane, thesteps comprising:

forming a plurality of apertures in the backplane; inserting plugs inselected apertures in said backplane to mask the surfaces of saidapertures;

forming a nonconductive coating on said backplane while said plugs arepositioned in said selected apertures;

thereafter removing at least some of said plugs from their respectiveapertures; and

mounting conductive elements in at least some of said aper-tures fromwhich said plugs are removed.

2. A method as set forth in claim 1 wherein: said backplane is formed ofaluminum; and said coating is formed by anodizing said backplane.

3. A method as set forth in claim 1 wherein: said plugs are connected toa common carrier strip prior to insertion into said selected apertures;and

said plugs are torn from said strip upon insertion into said apertures.

4. A method as set forth in claim 1 wherein:

said plugs are removed from said apertures by mounting said conductiveelements in said apertures.

5. In the method of manufacturing a backplane, the

steps comprising: 7

3 ,797 1 07 i 5 6 forming an aperture in an aluminum backplane; tionedin said aperture; and inserting a plug in said aperture to mask thesurfaces inserting a conductive element into said aperture to of theaperture; remove said plug therefrom. anodizing said backplane whilesaid plug is posi-

1. In the method of manufacturing a backplane, the steps comprising:forming a plurality of apertures in the backplane; inserting plugs inselected apertures in said backplane to mask the surfaces of saidapertures; forming a nonconductive coating on said backplane while saidplugs are positioned in said selected apertures; thereafter removing atleast some of said plugs from their respective apertures; and mountingconductive elements in at least some of said aper-tures from which saidplugs are removed.
 2. A method as set forth in claim 1 wherein: saidbackplane is formed of aluminum; and said coating is formed by anodizingsaid backplane.
 3. A method as set forth in claim 1 wherein: said plugsare connected to a common carrier strip prior to insertion into saidselected apertures; and said plugs are torn from said strip uponinsertion into said apertures.
 4. A method as set forth in claim 1wherein: said plugs are removed from said apertures by mounting saidconductive elements in said apertures.
 5. In the method of manufacturinga backplane, the steps comprising: forming an aperture in an aluminumbackplane; inserting a plug in said aperture to mask the surfaces of theaperture; anodizing said backplane while said plug is positioned in saidaperture; and inserting a conductive element into said aperture toremove said plug therefrom.